Indexing apparatus of various types have long been in use in conjunction with various types of manufacturing and assembly operations in order to advance workpieces between work stations as well as into and out of various types of machinery. Numerous types of drive systems have been developed over the years to accomplish this work transfer operation in a rapid and efficient manner. Typically, such drive systems have employed different combinations of barrel cams, bell cranks, lever arms, or scotch yoke connections and the like.
It is highly desirable to provide drive systems for such indexing apparatus which are able to smoothly move a workpiece through various work positions without subjecting either the workpiece or the associated apparatus to shocks or jerk resulting from sudden acceleration or deceleration from or to a stationary position. This is particularly important with regard to an apparatus which is designed for use in assembly operations wherein sudden movements may dislodge parts being assembled. Additionally, it is desirable to avoid abrupt movements in all cases because of the adverse effect which may result from subjecting the entire apparatus and workpiece to the stress and strain associated with such movements.
In addition to reducing or eliminating abrupt movement in such indexing apparatus, it is also desirable to design an apparatus to be able to reciprocate the workpiece into and out of various work positions as rapidly as possible. Also, to avoid successive down time as well as high maintenance costs, it is highly desirable to design such apparatus as simply as possible with a minimum number of moving parts. Coupled with a desire to maintain the design as simple as possible while still accommodating the other operational aspects required is the desirability of enabling the apparatus to be easily fabricated at a relatively low cost without sacrificing reliability. While previous indexing drive arrangements have been able to achieve differing measures of success in meeting the above objectives, none of them have been totally effective in providing a completely acceptable drive assembly that can secure a workpiece to allow work operations to be performed thereon at any point in its travel.
Consequently, a need exists for a substantially improved drive system which utilizes a cam and cam follower arrangements specifically designed to provide extremely smooth movement of a workpiece. Furthermore, a need exists for an apparatus which, while providing means to move said workpiece, also provides means to hold said workpiece in a secure position so that work may be performed thereon in any position the workpiece assumes during its travel. Likewise, a need exists for an indexing apparatus, which while providing first and second work positions for a workpiece, also provides various other work positions where access may be had to any surface of the workpiece, while simultaneously securing the workpiece to allow work operations to be performed thereon. Yet a further need exists for a user operated indexing apparatus that can be preprogrammed to halt the travel of the workpiece at any predetermined point to allow work operations to be performed thereon.